Preforms for blow molding plastic containers typically are produced in batch processes, in which one or more solid phase polymers such as polyethylene terephthalate (PET) are melted and injected into preform molds. The injection molded preforms are blow molded to form plastic containers, usually at some later time. A general object of the present invention is to provide a system and method for continuous production of blow molded plastic containers from molten polymer.
A system for making plastic containers in accordance with one presently preferred aspect of the invention includes a source for providing a continuous stream of molten plastic, and a cutter for severing a continuing series of individual mold charges from the continuous molten plastic stream. A compression molder includes a plurality of compression molds arranged in a continuing series for receiving the mold charges in sequence and compression molding the mold charges into a continuing series of individual plastic container preforms. A blow molder includes a plurality of blow molds arranged in a continuing series for receiving the individual plastic container preforms in sequence and blow molding the preforms into a continuing series of plastic containers. A common drive coordinates continuous and synchronous operation of the molten plastic source, the cutter, the compression molder and the blow molder to provide the continuing series of plastic containers from the continuous stream of molten plastic.
A method of making plastic containers in accordance with another aspect of the present invention includes providing a continuous stream of molten plastic, cutting the continuous stream into individual mold charges, and transferring the mold charges in sequence into a continuing series of compression molds. A continuing series of plastic container preforms are compression molded in the compression molds, and are transferred in sequence to a continuing series of blow molds. A continuing series of plastic containers is formed in the blow molds and removed in sequence. The step of transferring the preforms to the blow molds preferably includes conditioning the preforms preparatory to blow molding.
A system for making plastic containers in accordance with a third presently preferred aspect of the invention includes a source for providing a continuous stream of molten plastic, and a compression or injection molder for molding a continuing series of individual plastic container preforms. A blow molder includes a plurality of blow molds arranged in a continuing series for receiving the individual plastic container preforms in sequence and blow molding the preforms into a continuing series of plastic containers. A common drive coordinates continuous and synchronous operation of the molten plastic source, the preform molder and the blow molder to provide the continuing series of plastic containers from the continuous stream of molten plastic.